In the supervisory control of industrial plants there is continual requirement for information about equipment, current and historic process data, trends, etc. This information is typically provided by the control system and usually in the form of one or more distributed control systems (DCS) and/or supervisory control and data acquisition (SCADA) systems. The information is often presented to the operators through a display screen showing a process graphic that presents process data (measurements, values), tag identifiers, equipment ID, alarm status, connections between plant equipment, etc. As more and more data is being presented to the operators, the visual user interfaces often hold a great deal of information.
The task of finding the relevant technical information in a large information space is further complicated by the fact that in many situations the operator often has limited time available to make a decision. The significance of the information available will vary with the current situation. That is, users of industrial control systems have to deal at least in part with a context sensitivity problem, as in some contexts certain information will be essential and in others irrelevant.
In U.S. Pat. No. 6,002,398 entitled Navigation between property pages with tabs and menus, assigned to Novell, Inc., a method is described for displaying a tabbed dialog box, a property sheet, which has at least one child window. The parent window or property sheet has a multiple associated, displayable child windows. However at run time the described program loads all of the objects, including graphics, for all the child windows after user initiates the action which represents a heavy load on processor, display and system resources at runtime.
Operators and other users need to navigate to the correct process graphic as quickly as possible in a control system when a critical situation has occurred. Navigating wrongly can mean seconds are lost and can potentially be the cause of damages, delays or even a plant shutdown or accident. It is of great importance in systems where the response time is low—e.g. when the load time of the graphics are high—and may occasionally be crucial, to navigate to the correct graphic immediately, not having to load several process graphics first to check whether this is the one that is needed.
WO01/02953 describes a method for integration of many and various types of applications in a computerized system. This method is based on a concept where real world objects are represented as composite. Different facets of a real world object, such as its physical location, the current stage in a process, a control function, an operator interaction etc., are described as different aspects of the composite object. In this application, composite objects as defined by WO01/02953 are referred to as aspect objects.
Finding or retrieving the right information in control systems, of finding the right graphics to carry out monitoring or control, is often difficult because the information space is so large. There are often hundreds or thousands of process graphics, and the task of navigation is often difficult or time consuming. Operators must load the process graphic to see whether it is the desired process graphic, or not, which may result in unacceptable delay while searching for the required process graphic. Although different navigation schemes have been proposed they often demand considerable additional engineering or considerable system resources, or both.